Build ships without losing energy value to systems.
If you need fleets, but your systems are low or out of available energy slots, change the the destination of the construction to a neutral system (it can be habited or inhabited). The ship will still have a cost in maintenaince and refined points, but it will save energy.

Easy Fighter Killing
This is for places like Coruscant where there are a lot of fighters. Get a fleet really close to the enemy system. This fleet should have 2 Corellian Corvettes and 1 Escort Frigate (Nebulon B's if you have them) but NO FIGHTERS.
Jump into the enemy system and unpause. When the enemy fighters start moving, pause and jump into hyperspace. The fighters will have reached you and exchanged shots. If you were quick enough they won't damage you but their squad size will be reduced. Repeat as needed.

Fast start for the rebels
The empire allways begins with a planet that supports the rebellion, but is subjugated by a big garrison of ground troops. if you gather a large fleet with several fighter squadrons and put a commander with high leadership and combat (Han Solo or Wedge Antilles) you can easily blockade the planet. Then promote the commander to admiral status. Then bombard the imperial miltary units. Once you have destroyed all imperial units the planet automatically joins the rebellion. Liberating the planet will cause the rebellions popularity to skyrocket often causing several neutral systems to join and imperial systems to uprise. Then you can liberate the imperial system which are pro rebels and soon you control the whole sector. I once conquered an entire sector (sluissi) by day 34 using 2 corvette´s, and a fleet carrier carrying 4 Y-wing´s & 2 X-wing´s, commanded by Han Solo. P.S. You can prepare for planetary shields by having a good spy, like Chewbacca tagging along.

Power-up Luke
Later in the game, once you've blockaded Coruscant, put Luke on the blockading fleet. SAVE THE GAME! 99% of the time, the Emperor or Darth Vader (or both)will be on the planet. Send Luke on a sabotage mission or capture mission (but make sure not to target the Emperor!) Since the Vader and/or Emperor are both force users, they'll detect Luke. His mission will be foiled and he will gain two force bonuses: One for encountering Vader/Emperor and another for evading escape. If Luke gets captured, reload the game and send a few infiltrators in with him. Even if he fails then, keep on trying and repeat the process. Before you know it, he'll become super strong and darn near invincible. I had him over 500 in combat and espionage and 350 in diplomacy!

Take a planet
First target an enemy system and bulid 8 either bulwark battlecruisers or 8 super star deystroyers and commence a planetary bombardment (which will deystroy all their defenses) then invade the system with 12 or more regiments (this should elimanate all chances of a uprising) then continue to run diplomacy missions until the planet is loyal to you.

Take a planet...the easy way
Chose a planet you wish to take over. Invade with a fleet large enough to hold the system. Once you have a blockade of the system bring a strong force character (jedi Luke or vader) onto one of the ships. Send them to take out whatever generals they have controlling ground forces. Once thats done you can send them to take out the shields and defenses as many times as necessary with very little risk to themselves. After defenses are down you can incite uprising until they turn to your side without losing any ground forces or wasting time with diplomacy.